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Optical imaging has undergone a "digital" revolution in the past years due to the wide availability of powerful computing hardware, optical devices such as spatial light modulators, and low-cost, high quality detectors including CCD and CMOS cameras. In particular, the emergence of digital techniques that explicitly model the propagation of light has revolutionized optical imaging through digital holography and digital holographic microscopy. These techniques offer many advantages over conventional imaging optics such as: capturing the full complex wave in amplitude and phase; adjusting the focus of an image after the image is captured; eliminating aberrations or imaging through scattering media; or allowing the freedom to choose any imaging modality, e.g. phase vs. amplitude contrast, on-the-fly. Intriguingly, digital holography and related techniques allow the capture of an image without the use of any lenses. Indeed, high-resolution, diffraction-limited performance is easily achieved. All of this is possible through the central idea of holography: directly capturing the interference pattern between a known and stable “reference wave” and an unknown and perhaps dynamic “object wave” that reflects from or transmits through a sample of interest, shown in figure 1a. These interference patterns were historically captured on analog film. Modern digital versions capture the hologram pattern directly on a high-density CCD or CMOS imager chip, shown in Figure 1b. While laser sources are typically used, in some cases it is also possible to use LEDs.
If remote participation in the Immersion becomes necessary, participants will need a computer and MATLAB for hologram analysis. If participants want to also make their own holograms, then a laser, CCD or CMOS camera (a digital SLR camera will work), and some basic optics (posts, lenses, mirrors, etc...) would be necessary, depending on the complexity the participants wanted.
Figure 1. (a) Holography concept. (b) Sample digital holography apparatus.
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